Tear away or contact fastening systems are well known. Such systems incorporate two opposing segments of material which are engageable in substantially juxtaposed relation to one another. A male portion of such a contact fastening system typically incorporates a plurality of outwardly projecting hooking structures, while the female portion incorporates a plurality of outwardly projecting loop structures. Upon engagement between the two cooperating portions, the hooking structures engage the opposing loop structures thereby establishing a bond. This bond may be broken by the application of a peeling action between the two opposing portions of material thereby permitting the male and female portions to be progressively disengaged from one another. The engagement may be reactivated by simply bringing the male and female portions back into contacting juxtaposed relation with one another.
Stitch-bonding is a known process in which yarns are stitched through a substrate to form a coordinated web structure. By way of example only, and not limitation, exemplary stitch-bonding processes are disclosed in U.S. Pat. Nos. 6,855,392; 6,869,660; and 7,294,387 all of which are incorporated by reference as if fully set forth herein. In the past, stitch-bonding has been used in the manufacture of loop face composite material to form the loop portion of a tear-away fastening system in a diaper using an LDPE film at the stitching substrate. By way of example only, and not limitation, such materials are disclosed in U.S. Pat. No. 8,632,517 to Wildeman et al., the contents of which are incorporated herein by reference in their entirety.
A benefit of using a film as the stitching substrate in prior loop face composite materials is that even with the piercing of the stitch-forming needles, the resulting stitched composite maintains a low Frasier air permeability of about 25 cubic feet per minute (CFM) when measured according to ASTM D737. Maintaining low air permeability is important in the processing of the stitch-bonded material during diaper production.
According to one exemplary diaper formation practice, a continuous roll of the stitch-bonded material (ranging from about 140 mm-180 mm width) may be fed into a diaper machine and a hot melt adhesive is applied to the non-loop side of the material. The fabric then is cut into a part that the machine then adheres onto the front of the diaper. During this attachment procedure, a vacuum drum or belt is used to control and transport the cut part for assembly onto the diaper. In the event that the stitch-bonded material is too permeable to air flow, the vacuum system may have difficulty in controlling the cut part, and the attachment procedure may be compromised.
While the film substrate provides excellent performance, one potential deficiency of using a film substrate is that some users may prefer a material having a more fabric-like feel. In order to address this preference, attempts have been made to substitute a nonwoven polypropylene spunbonded substrate in place of the film. However, the air permeably of the resulting material was too high to permit reliable use with the vacuum system of the diaper formation machine.
Accordingly a stitch-bonded loop face composite incorporating a nonwoven substrate to impart a fabric feel while maintaining a suitably low air permeability to operate with a diaper machine vacuum system would be of substantial benefit.